Like apparently everything else on the planet nowadays, it's on amazon.
Taint cheap, but here ya go.
Amazon.com: Encyclopedia of Chevrolet Trucks...
Option 2 - just ask, and someone on here will know the answer to any quesiton. But the book does look like a good ref manual. but keep in mind, it's not just 60-66 trucks, so of the 320 pages, probably only a portion is dedicated to our series of interest. Anyhoo, there ya go. If you want a good reference and enjoy all the years, not just 60-66, you might enjoy. Couple used ones listed for sale also, but STILL not cheap! It MUST be good...